960H CCTV Aspect Ratio Correction

Published: 06 January 2018 on DME Resources

A couple of years ago I did a series of posts on aspect ratio correction of DCCTV recordings; more specifically DCCTV recordings captured by analog CCTV cameras, and correcting Display Aspect Ratio (DAR) for forensic interpretation. I pointed out in my posts and the subsequent Video & Display Standards Chart, that the one exception that I'm aware of where a DCCTV recording captured by an analog CCTV camera shouldn't be displayed 4:3, was the relatively new 960H format.

True 960H capability requires both a 960H capable camera (sensor) AND a 960H recorder, and when the system is configured properly the resulting recordings should be displayed 16:9. Unfortunately, some 960H recorders are being sold packaged with traditional 4:3 analog CCTV cameras, and of course no explanation of the related issues. We also have those that buy/implement a 960H recorder OR 960H camera, not realizing they need both to leverage 960H properly. In gist, more confusion, more substantially distorted recordings.

With all that said, here’s how I correct 960H NTSC for the two most common scenarios:

• 960H recorder AND 960H camera (may store at either 960 x 480 or 928 x 480) I would correct to 854 x 480 for proper 16:9 DAR.
• 960H recorder using a traditional 4:3 NTSC camera (may store at either 960 x 480 or 928 x 480) I would correct to 640 x 480 for proper 4:3 DAR.

I have not dealt with 960H PAL material yet personally, but would probably try:

• 960H recorder AND 960H camera (may store at either 960 x 576 or 928 x 576) I would correct to 1024 x 576 for proper 16:9 DAR.
• 960H recorder using a traditional 4:3 PAL camera (may store the video either at 960 x 576 or 928 x 576) I would correct to 768 x 576 for proper 4:3 DAR.

“Try” being the optimum word there. In all cases I’d of course compare to see if the correction affected interpretation in regards to the questions being asked.

So we should always maintain the height and correct the width for both NTSC & PAL, except for field-based storage dimensions such as 704x240 NTSC or 704x288 PAL (where we have to double the lines first)? ?Does it matter that the resulting DAR corrected image’s pixel dimensions exceed the effective pixel array of the source sensor when correcting PAL material using this methodology (i.e. 768 x 576 or 1024 x 576 examples)?

Well, I have my opinions of course, but I'd love to hear yours. DCCTV evidence Aspect Ratio Correction is a topic that should be further discussed & researched openly within the community, IMHO. Hoping this post gives some folks a little food for thought. As always, thanks for reading. Be safe out there my friends.